The present invention relates to a knob adjustment device, in particular for adjusting the temperature in water-heating apparatus, according to the preamble to the main claim.
The invention relates in particular to the field of water-heating apparatus such as, for example, domestic water heaters, in which there is a thermostatically-controlled valve unit provided with a knob adjustment device for adjusting the temperature of the water to be heated.
An example of an adjustment device of this type is described in the Applicant""s patent application No. PD2000A000185.
The above-mentioned knob adjustment device is arranged to incorporate the operative control functions by means of which the user can permit lighting of the pilot-light and shutting-off of the gas-flow and, in addition, can select the desired water-temperature value. These functions can be selected by the user by rotation of the above-mentioned knob device.
Within this technical field, a need has arisen to ensure safety locking of the knob to prevent its accidental rotation during the operation of the water-heater, which could lead to undesired and, in some cases, dangerous increases in the water temperature. A typical condition to be prevented is that in which accidental operation of the knob, for example, by children, may lead to an increase in the water temperature such that it is dangerous in use.
A main object of the invention is to provide a knob adjustment device of the above-mentioned type which is designed structurally and functionally to satisfy the need indicated, ensuring safety locking of the knob when the water-heater is in operation, and which can prevent undesired accidental rotation.
Another object is to provide a knob adjustment device in which rapid operation of the knob from the safety locking position towards a switched-off position or, in any case, a position in which the water temperature is reduced, is permitted so as to ensure that the device is made safe quickly if conditions dangerous to the user should arise.
These and other objects which will be made clear below are achieved, according to the present invention, by a knob adjustment device, in particular for water-heating apparatus, having the characteristics set out in the appended claims.